During order fulfillment operations such as stocking and picking in a storage location such as a warehouse, a common source of inaccuracy is caused by a stocker or material handler stocking (or picking) a product at an incorrect location.
Some systems, such as pick to voice, address this by requiring the material handler to read a confirmation code that is printed at each location to verify that they are in fact at the correct spot, picking or stocking the correct item. This solution however, is fallible as it is common for the material handlers to memorize these confirmation codes and speak back the correct code to the system while picking/placing at an incorrect location.